Zemeraire
Songster
Can you explain further about the others genetic combinations besides extended black to create black?
The more common black in silkies is eb/eb S or s+ Pg/Pg Ml/Ml and other melanisers (such as charcoal). Im not sure exactly how this one works, but I got the information from here https://silkie.org/silkie-colours.html
I think the above black is the slightly duller/earthy toned "non shiny" black some people talk about, while the "shiny" blacks with more sheen on them are extended blacks.
Also while trying to figure out the genetics of one of my hens who threw VERY wierd babies, I found that IN THEORY eR/eR (birchen) plus double charcoal can result in solid black. Charcoal is very common in silkies (where I am at least), it causes the darker heads on greys or partridges that I know some people don't like.